Pressure vessels



April 30, 1963 J. J. HAFTKE 3,037,833

PRESSURE VESSELS Filed Oct. 27, 1958 2 Sheets-Sheet 1 April 30, 1963 J. J. HAFTKE PRESSURE VESSELS 2 Sheets-Sheet 2 Filed Oct. 2'7, 1958 United States Patent 3,037,883 PRESSURE VESSELS Jozef J. Haftke, London, England, assignor to Babcock &

Wilcox Limited, London, England, a company of Great Britain Filed Get. 27, 1958, Ser. No. 769,615 Claims priority, application Great Britain Oct. 28, 1957 Claims. (Cl. 204-1933) This invention relates to large pressure vessels of the kind including a shell of which for greater strength the lower portion is dished and is particularly concerned with vessels of this kind in which the shell is bottom supported and an internal structure is bottom supported within the shell. A typical example of such a pressure vessel is that of a gas cooled graphite moderated nuclear reactor including a core the size and weight of which are such that the dimensions of the shell required to accommodate it are large.

According to the present invention there is provided a large pressure vessel including a shell of which the lower portion is dished and contains a narrow annular part with its center on, or substantially on, the vertical axis of the shell, and in which one portion of the shell is butt-welded to the inner periphery of the annular part and another portion of the shell is butt-welded to the outer periphery of the annular part, the annular part being provided with a downwardly extending annular projection or with a plurality of downwardly extending projections spaced around the annular part and with an upwardly extending annular projection or with a plurality of upwardly extending projections spaced around the annular part, means for bottom supporting the shell butt-welded to the lower edge or edges of the downwardly extending projection or projections and means for bottom supporting an internal structure within the shell butt-welded to the upper edge or edges of the upwardly extending projection or projections, the annular part being such that its transverse thickness adjacent any weld between the annular part and a component connected to either of the peripheries of the part or to the edges of the projections is substantially the same as the transverse thickness adjacent the Weld of the component connected to the annular part by the weld.

With this arrangement the welds connecting portions of the pressure vessel shell to the annular part, the Welds connecting the means for bottom supporting the pressure vessel to the shell and the welds connecting the means for bottom supporting the internal structure from the shell are all such that they can be inspected by radiographic means and rigorous inspection by such means is desirable in view of the stresses to which the welds are subjected. Moreover, the location of the welds is such as to facilitate their formation, with the consequently greater likelihood that stress raising cavities will be avoided.

In the formation of the annular part the upwardly and downwardly extending projections can be readily disposed in any predetermined locations relatively to each other so that the location of the means for bottom supporting the shell relatively to the means for bottom supporting the internal structure can readily and positively be determined. In particular, it can be arranged that the two means are situated one immediately above the other with the consequent advantage that any bending moments on the shell resulting from the weight of the internal structure can be minimised. It will be realised that in a gas cooled, graphite moderated nuclear reactor, the core is necessarily of considerable size and weight. The enclosing pressure vessel shell is therefore of corresponding large dimensions and, in view of the operating pressure of the coolant and the temperatures to which the shell is subjected in operation, the shell is of necessity 0 part 5 will be described in more detail later.

3,087,883 Patented Apr. 30, 1963 thick. Considerable stresses are therefore inevitably involved and a reduction of additional stresses resulting directly from the weight of the core is highly desirable.

By way of example, an embodiment of the invention will now be described with reference to the accompanying drawings in which:

FIGURE 1 shows somewhat diagrammatically, half of a vertical section of a nuclear reactor pressure vessel including a spherical shell that is bottom supported and cgntains means for bottom supporting a core within the s ell;

FIGURE 2 shows in plan a portion of an annular part of the shell shown in FIGURE 1;

FIGURE 3 is a transverse section on the line IIIIII of FIGURE 2; and

FIGURE 4 is a transverse section on the line IVIV of FIGURE 2.

The spherical shell, indicated by 1, has a diameter of sixty-seven feet and is formed generally from plates buttwelded at their edges. It includes the debris removal nozzle 2 welded into the circular bottom plate 3. A first course of ten petal-like plates 4 extends upwardly from the plate 3 to the narrow annular part 5 and is welded to the inner periphery of this part. The annular A second course of eighteen plates 7 is welded to the outer periphery 8 of the annular part 5, and the shell is completed by a third course of eighteen plates 9, a fourth course of eighteen plates 10, a fifth course of eighteen plates 11, a sixth course of twenty plates 12, a seventh course of thirteen plates 13, an eighth course of 8 petal-like plates 14 and the circular top plate 15. All the plates of each course have the same contour although six of the plates 7 are provided with apertures containing the gas inlets 16 and eight of the plates 12 are provided with apertures containing the gas outlets 17. Many other nozzles and apertures are provided in the shell 1 for example to provide access to the core and to enable various testing and measuring instruments to be included, but for the sake of clarity, these are not shown in the drawings.

The annular part 5 is in the form of a ring of cruciform section. The diameter of the inner periphery 6 of the ring is thirty feet and the part 5 includes the shell part 18 provided with a downwardly extending ridge 19 and an upwardly extending ridge 20. The part 5 presents four major surfaces 21, 22, 23 and 24 respectively. The edges of the surface 21 lie respectively at the outer periphery 8 and the rim 25 of the projection 20. The edges of the surface 22 lie respectively at the rim 25 and the inner periphery 6. The edges of the surface 23 lie respectively at the inner periphery 6 and the rim 26 of the projection 19 and the edges of the surface 24 lie respectively at the rim 26 and the outer periphery 8.

The annular part 5 is formed from fifteen arcuate sections 27 of equal length butt-welded end to end. Each section is formed by a hammer forging process or by pressing and bending and a part of both the projections 19 and 20 is formed integrally with the part of the ring 18, the parts of the projections stopping short of the ends of the part of the ring 18. In forming the annular part 5, the sections are butt-welded end to end at 28. Since these welds are made between members of the same substantially rectangular section they can be readily made and tested. After the formation of these welds, filler pieces 29 are fixed in position between the ends of the parts of the projections 19 and 20 that are formed on the sections 27, the filler pieces being welded at their ends 30 and at their bases at 31.

Extending downwardly from the annular part 5 is the continuous skirt 32, butt-welded at its upper edge to the rim 26 of the projection 19. The lower edge of the skirt 32 carries a flange 33 and the flange 33 rests on a circular series of piers 34 set in concrete 35.

A further continuous skirt 36 extends upwardly from the annular part 5 and is butt-welded at its lower edge to the rim 25 of the projection 20. Skirt 36 is provided at its upper edge with a flange 37 on which the core of the reactor is mounted through a grid of any suitable construction. The core is of known form and is not illustrated.

Both the skirts 32 and 36 are formed from curved, substantially rectangular plates welded together at their edges. They are of the same diameter and situated one immediately above the other so that the core exerts no bending stresses on the shell.

As is apparent from FIGURES l, 3 and 4, the thickness of the annular part 5 in the vicinity of the peripheries 6 and 8 is the same as that of the plates that are welded to the peripheries. Similarly the thicknesses of the projections 19 and 20 in the regions of the rims 25 and 26 are substantially the same as those of the skirts 32 and 36 connected to the rims 2S and 26 respectively. This not only allows free access to the welds so facilitating their formation, but also enables the welds to be tested satisfactorily by radiographic means since there are no dissimilar thicknesses of the weld that would cause diffraction of, or other interference with, the rays that would render the results of the tests unreliable.

The embodiment described may be modified in many ways. For instance a narrow ring of plates may be interposed between the outer periphery 8 of the annular part 5 and the plates 7 forming the second course in the FIGURE 1. The plates in this narrow ring might be in the form of extensions of the plates 4. Either or each of the projections 19 and 20 should be replaced by a series of projections spaced around the annular part 5 and the means for bottom supporting the shell 1 and for bottom supporting the core could have a more skeletal form than is shown in the drawings.

Although the bending stresses in the shell produced by the core are a minimum when the means for bottom supporting the core lies, as shown, immediately above the means for bottom supporting the shell, it is possible for the two to be somewhat displaced relatively to each other without introducing an intolerable bending moment.

I claim:

1. A large pressure vessel for enclosing and supporting a heavy internal structure and including a shell of which the lower portion is dished and contains a narrow annular part integrally formed substantially as a cruciform section with its center axis substantially on the vertical axis of the shell, and in which one portion of the shell is butt-welded to the inner periphery of the annular part and another portion of the shell is butt-welded to the outer periphery of the annular part, the annular part being provided with a downwardly extending annular projection and with an upwardly extending annular projection, means for bottom supporting the shell butt-welded to the lower edge of the downwardly extending projection and means for bottom supporting an internal structure within the shell butt-welded to the upper edge of the upwardly extending projection, the annular part being Car Cit

such that its transverse thickness adjacent the weld between the annular part and a component connected to one of the peripheries of the part is substantially the same as the transverse thickness adjacent the weld of the component connected to the annular part by the weld.

2. A pressure vessel as claimed in claim 1 and being a nuclear reactor pressure vessel, the internal structure being the nuclear reactor core.

3. A pressure vessel as claimed in claim 1, in which the means for bottom supporting the internal structure lies immediately above the means for bottom supporting the shell.

4. A pressure vessel as claimed in claim 1, in which at least one of the means for bottom supporting the shell and the means for bottom supporting the internal structure is in the form of a skirt.

5. A pressure vessel as claimed in claim 1, in which the means for bottom supporting the internal structure is in the form of a skirt and the skirt is butt-welded at one end to the rim of a single annular projection provided on the annular part.

6. A pressure vessel as claimed in claim 1, in which the annular part is formed from a number of arcuate sections butt-welded end to end.

7. A pressure vessel as claimed in claim 6, in which the annular part is provided with an extending annular projection and the annular projection runs continuously from one arcuate section to another and includes two portions each formed integrally with one of the two said arcuate sections and ending short of the end of the section at which the section is welded to the other section, the projection also including a filler member welded in position and extending between the neighbouring ends of the two portions.

8. A pressure vessel as claimed in claim 1, in which the annular part is provided with a downwardly extending annular projection and with an upwardly extending annular projection and the annular part presents four concavely curved surfaces each having one edge lying at a periphery of the annular part to which a portion of the shell is welded and the other edge lying at the rim of one of the upwardly and downwardly extending annular projections.

9. A pressure vessel as claimed in claim 8, in which the concavely curved surfaces merge into faces of the components welded to the inner and outer peripheries of the annular part and to the rims of the projections.

10. A pressure vessel as claimed in claim 8, in which the shell is spherical and the diameter of the shell is much larger than the diameter of both the inner and outer peripheries of the annular part.

References Cited in the flle of this patent UNITED STATES PATENTS 797,577 Heylandt Aug. 22, 1905 2,577,171 Wiggins Dec. 4, 1951 2,730,798 Larsen Jan. 17, 1956 2,768,432 Hines Oct. 30, 1956 OTHER REFERENCES Nuclear Power, vol. 2, p. 397 (II), October 1957. 

1. A LARGE PRESSURE VESSEL FOR ENCLOSING AND SUPPORTING A HEAVY INTERNAL STRUCTURE AND INCLUDING A SHELL OF WHICH THE LOWER PORTION IS DISHED AND CONTAINS A NARROW ANNULAR PART INTEGRALLY FORMED SUBSTANTIALLY AS A CRUCIFORM SECTIONN WITH ITS CENTER AXIS SUBSTANTIALLY AS A CRUCIVERTICAL AXIS OF THE SHELL, AND IN WHICH ONE PORTION OF THE SHELL IS BUTT-WELDED TO THE INNER PERIPHERY OF THE ANNULAR PART AND ANOTHER PORTION OF THE SHELL IS BUTT-WELDED TO THE OUTER PERIPHERY OF THE ANNULAR PART, THE ANNULAR PART BEING PROVIDED WITH A DOWNWARDLY EXTENDING ANNULAR PROJECTION AND WITH AN UPWARDLY EXTENDING ANNULAR PROJEDCTION, MEANS FOR BOTTOM SUPPORTING THE SHELL BUTT-WELDED TO THE LOWER EDGE OF THE DOWNWARDLY EXTENDING PROJECTION AND MEANS FOR BOTTOM SUPPORTING AAN INTERNAL STRUCTURE WITHIN THE SHELL BUTT-WELDED TO THE UPPER EDGE OF THE UPWARDLY EXTENDING PROJECTION, THE ANNULAR PART BEING SUCH THAT ITS TRANSVERSE THICKNESS ADJACENT THE WELD BETWEEN THE ANNULAR PART AND A COMPONENT CONNECTED TO ONE OF THE PERIPHERIES OF THE PART IS SUBSTANTIALLY THE SAME AS THE TRANSVERSE THICKNESS ADJACENT THE WELD OF THE COMPONENT CONNECTED TO THE ANNULAR PART BY THE WELD. 